Special Issue: Additive Manufacturing (AM) and 3D Printing

Additive manufacturing (AM) is currently experiencing a renaissance of interest and activity worldwide. For those of us who have been in the field from the beginning, it is reminiscent of the “first hype” in the early to mid-1990s. At that time, the surge in interest started with a few companies and research universities that were engaged in AM, and the interest was confined to users who were intrigued by the novelty and potential. The current wave of interest is much broader. There are several factors that contributed to this. First is the explosion of low-end 3D printers that were adopted by hobbyists and do-it-yourselfers. Two of the earliest manifestations were Hod Lipson's Fab@Home unit and the RepRap Project. The UP! Machine from China and the Makerbot unit in the United States are popular versions of more recent incarnations. The increased societal awareness of these low-cost, open source fabricators has resulted in the general public becoming aware of the technology. At this writing, a major office supply chain is marketing a low-end printer in their on-line store catalog.The second factor leading to the explosion of interest in AM is the expiration of founding patents from the 1980s and early 1990s. This enabled the “Makerbot Craze” and will have a significant impact on the AM equipment landscape in the next five years as competing high-end fabricators enter the market. It is foreseeable that, as always, an increase in competition fueled by patent expiration will result in lower capital cost for the AM equipment as well as variegation in quality and service.The third factor contributing to the focus on AM is the realization among governmental policy makers that manufacturing means jobs, and that advanced manufacturing represents a collection of technologies with potential to shore up domestic economies. President Obama's 2012 announcement of a new series of advanced manufacturing innovation institutes with AM as the harbinger technology of the group has not only made “3D Printing” a household word; it has created associated resonances across the world, including in Europe and China, two other large economic powerhouses. The first of these institutes is “America Makes,” charged with accelerating the transfer of AM technologies from the laboratory into the stream of commerce.Behind this interest and hype stands years of research and development. The International Annual Solid Freeform Fabrication Symposium—An Additive Manufacturing Conference last August celebrated its 25th anniversary. The meeting is an academic, high-level research conference that provides a forum for presentation of AM research and interaction/collaboration among the AM research community. The 1400 papers published in the Proceedings over the last 25 years reflect, along with other publication outlets, the depth and breadth of research in the field over a long period of time.This special issue on AM is a testimony to the depth and breadth of AM technology as well as the variety of research undertaking. Coverage includes improvements in low-end and high-end printers, advances in precommercial AM processes, process monitoring and control, improvements to part quality, physical modeling of processes, bioprinting, novel materials, and process improvement.The guest editors appreciate the contributions of the authors of this special issue on additive manufacturing as well as the larger technologies that these contributions represent.